Though… discernment may have a basis in natural shrewdness, it comes to fruition only through a sustained attunement to God and a habit of asking himself at every point in life what makes for His glory (that is, His own self-expression and His creatures’ appreciation and adoration of Him).

J. I. Packer, A Passion for Faithfulness (Wheaton, IL: Crossway Books, 1995), 134.